David, thanks for that link. I have I think made all those points about this issue in my posts over the years.
I would first reiterate, the author's admonition, that tearing out the passive crossover from a speaker, and replacing it with an active crossover is not a simple problem. There are increasing number of members who think it is. As the author points out if is a difficult and complex problem.
In addition I would add the following, and most of these points are eluded to by the author, however he glossed over my first point.
In an analog filter, whether active or passive, the phase shifts and time delays will still be dependent on order. So both passive and active fourth order filters will turn a square wave into a sine wave. I know WmAx is going tell me that is of no consequence, but a defect as gross as that has to be of significant consequence. I know it is an issue and but almost impossible to AB, as changing filter orders changes the whole balance of a speaker, and using different drivers is confounding.
In the past active speakers have by necessity been expensive. However we now seem to be able to produce large numbers of amps in receivers at very modest cost.
Making a decent passive crossover is costly to manufacture. At the price point of speakers talked about most often on these forums, they have to have dreadful quality crossover parts. The cost of good crossover parts alone, would exceed the total cost of many speakers talked about here.
I believe therefore that active speakers could be produced competitively.
However as home theater increases in complexity, it gets into the hands of fewer and fewer large manufacturers. Large corporations have zero imagination, and slavishly follow the familiar well traveled road.
In my view adding increasing processing power and increasing numbers of amps to receivers is a flawed engineering concept certain to end in grief. I counsel anyone against the purchase of such a devices.
Obviously if pre pros were a high demand item, they could be produced for half the coat at least of a receiver, may be less.
So that would give you a good leg up on the production of active speakers, especially with the savings from the elimination of the passive crossover as well.
The next issue is R & D. There really is advantage in having steep crossover slopes quite often. The problem is high order slopes, with the phase shifts and time delays, make the speakers sound somewhat slugged to me.
So far perfect phase digital crossovers have been the preserve of a small
Australian company DEQX.
What is required is some deeper pockets to run with this ball.
What I would envision is speakers powered by small class A amps for the tweeters, a class AB amp preferably a current dumper for the mid or bass mid, and a class D for the bass if a three way or two and a half way. May be class D is already good enough for the lower two, I don't know.
Then if it was all put together with zero phase digital crossovers you would really have something.
We badly need someone of Peter Walker's drive for innovation for this. I know that if he was still with us he would be there already. As it is he did the spade work for the active Quad's talked about here. He engineered the powering of the legendary BBC active TLs.
Doing this right is a tall order for the home constructor. To be practical for most you need a supply of suitable amps in board form. Heat sinks and casings have to be fashioned. Building the crossover is not bad, and there are design programs for active filters now, well within reach of the home constructor. For that reason for the home constructor the amps and crossovers are remote from the speakers, which makes for a "busy" complex installation.
I just wish audio and home theater enthusiasts would wake up and realize how short changed they are by the current state of play. I think any manufacturer willing to "Go Rogue" would reap the rewards.
May be threads like this will help to educate.
One more thought, always run speaker wire in conduit, not just in wall. I hope you will not need those speaker wires much longer, but balanced audio or optical cables instead!
